What is the different between variable == 1 and variable = 1?

the double equal (==) is used for testing equality.  the single equal (=) is the assignment operator.

var1 = 1;  // assigns the value of 1 to the variable var1

if(var1==1){

// this executes if var1 has a value of 1

} else {

// this executes if var1 has a value other than 1

}